Sometimes I completely drain the housing and rinse the inside with a lab wash bottle filled with clean diesel. Then sometimes I'm a bit lazy, and just drain enough to remove the old element and put a new one in there.

Keith* -* On our low gph trawlers, IMHO cleaning a 900*bowl completely with each filter change is largely just for peace of mind. If you see some gunk or water in the bowl, sure clean it totally. Some 900s like ours see 2-4 gph, others see 20 - 40 gph. Big difference.

I commend all of you that do a thorough cleaning when changing filters. I must admit that despite my knowledge that clean fuel is the most important ingredient to continued operation of a diesel, I am a little careless, and have never (knock on wood) had a fuel problem. Every time I've changed filters in the last twelve to fifteen years, I have faced what appeared to be a clean bowl, so all I have done is replace the two Racor 900s, top off the fuel in the bowl and put it back together. Pump a little fuel with the primer, and off we go. I do change the primary Cat filter at the same time.*Cheers, Carey

"Just where does the18 to 35 gallons per hour go that the engine does not burn. This makes no sense."

The DD use mechanical injection where each individual injector IS the injection pump.

A look with the valve cover off will show 3 rocker arms lined up , two open the exhaust valves so the blower can push out the last bit of spent gas , the 3rdr one is timed and the injection is caused by its rocker arm's motion.

The reason this is done was so the engine could be built up facing in any direction , or its output rotation reversed with just a few gaskets, and parts moved.

Also it adds to the engines reliability as each injector would have to fail , not just a common pump.

The fuel goes thru the cylinder head cooling the injectors and of course feeding them as required.

Since lots more fuel is required to cool than gets burned the filters must be of a good size. We use 1000's .

The only hassle is to get the engine to operate smoothly ALL the injectors need to be timed exactially together.
This is the famous "Running the Rack" and is best done by a guy with lots of practice.

Although an amateur with patience ( AND DA BOOK!) can do a good enough job for the engine to operate tens of thousands of hours , but not as smoothly or as efficiently as a pro.

*Peter B wrote:Goes back to the tank via the fuel return feed.* Or, as in my case, the primary filter, and just keeps going round, and round.
*Capn Chuck wrote:If your return line is circulating 20 to 35 gallons of fuel per hour, you have a serious problem or an EXTREMELY large engine. Chuck

Quite right Chuck, but I was only answering the query, "So Fred, Just where does the18 to 35 gallons per hour go that the engine does not burn. This makes no sense. Chuck", posted by youself?* Mine does not recirculate anything like 35gph.

"If your return line is circulating 20 to 35 gallons of fuel per hour, you have a serious problem or an EXTREMELY large engine. Chuck"

The fuel pump on the 71 series inline engines that FF references pumps 40 gph at rated rpm. That means the fuel returned is* whatever is not burned and at low loads that could easily be 35 gallons per hour or more depending on whether it is a 2, 3, 4, or 6 cylinder engine.

There is no serious problem and none of those engines would be described as EXTREMELY large unless you are trying to put one in a model boat.

My 4-53 DD circulates around 35 gph with a consumption of 2 to 3 gph. The high flow is required to cool the injectors and the only problem I have had, was a return line on the engine giving way and pumped about ten gallons of clean fuel ALL OVER THE ENGINE ROOM. The only down to this arrangemnt may be the high volume of hot fuel being returned into a low fuel tank.